<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    function yuer(){
      let yuer = +prompt('输入银行卡的余额')
      let shisufei = +prompt('输入食宿费金额')
      let shenghuofei = +prompt(`输入生活费金额`)
       yuer= yuer - shisufei- shenghuofei
     return document.write(`银行卡剩余金额${yuer}`)
    }
   let re=yuer()
console.log(re)
  </script>
</body>
</html>